From: Robert Roessler <roessler@rftp.com>
To: Caml-list <caml-list@inria.fr>
Subject: Re: [Caml-list] Severe loss of performance due to new signal handling
Date: Mon, 20 Mar 2006 17:33:49 -0800 [thread overview]
Message-ID: <441F57FD.90206@rftp.com> (raw)
In-Reply-To: <441E760D.6010801@inria.fr>
Xavier Leroy wrote:
> > It seems that changes to signal handling between OCaml 3.08.4 and 3.09.1
> > can lead to a very significant loss of performance (up to several orders
> > of magnitude!) in code that uses threads and performs I/O (tested on
> Linux).
> > [...]
> > Maybe some assembler guru can repeat this result and explain to us
> > what's going on...
>
> Short explanation: atomic instructions are dog slow.
At the risk of being "irrelevant", I wanted to nail down exactly what
assertion is being made here: are we talking about directly executing
in assembly code the relevant x86[-64]/ppc/whatever instructions for
"read-and-clear", or going through OS-dependent access routines like
Windows' InterlockedExchange()?
Or: is the source of the dog slow behavior because of OS overhead, or
is it a low-level issue like memory barriers/cache lines getting
flushed/something else?
Robert Roessler
roessler@rftp.com
http://www.rftp.com
next prev parent reply other threads:[~2006-03-21 1:33 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-03-17 18:39 Markus Mottl
2006-03-17 19:10 ` [Caml-list] " Christophe TROESTLER
2006-03-20 9:29 ` Xavier Leroy
2006-03-20 10:39 ` Oliver Bandel
2006-03-20 12:37 ` Gerd Stolpmann
2006-03-20 13:13 ` Oliver Bandel
2006-03-20 15:54 ` Xavier Leroy
2006-03-20 16:15 ` Markus Mottl
2006-03-20 16:24 ` Will Farr
2006-03-21 1:33 ` Robert Roessler [this message]
2006-03-21 3:11 ` Markus Mottl
2006-03-21 4:04 ` Brian Hurt
2006-03-21 12:54 ` Robert Roessler
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